System and method for routing VoIP calls

ABSTRACT

A method of routing a voice call from a local media gateway to a terminating media gateway comprises determining IP network connectivity between the local media gateway and terminating media gateway and generating monitoring results, updating network resource status according to the monitoring results, generating a plurality of routes between the local media gateway and the terminating media gateway in response to the updated network resource status, determining a best route from the plurality of routes, and routing the voice call using the best route.

BACKGROUND

Connectivity and voice quality are key reliability issues in today's VoIP (voice over Internet Protocol) networks. Today's VoIP users increasingly expect the Quality of Service (QoS) of the call to be equal or close to that of the Public Switched Telephone Network (PSTN). Because network conditions may change rapidly and continuously, connectivity for a VoIP call cannot be guaranteed. Further, IP network problems such as packet loss, packet delay, and out of order delivery may lead to deteriorating quality of VoIP voice calls.

Unlike data connections, a real-time application like voice calls place much stricter requirements on packet delivery sequence and time. Significant packet loss, packet delay, and out of order delivery problems make telephone conversations difficult. Users may experience echoes and talk overlap that are perceived as significant indicators of inferior QoS.

Previously, voice call routing only exists in the voice network domain, which is characterized by logical trunk groups interconnecting switches in the network. Voice routing in this context involves routing on circuits or logical trunk groups. The IP network routing function previously only operate in the data network domain and is not operable with the applications operating in the application layer. Therefore, routing voice calls on a data network to satisfy QoS remained a challenge unconquered by the industry.

BRIEF DESCRIPTION OF THE DRAWINGS

Aspects of the present disclosure are best understood from the following detailed description when read with the accompanying figures. It is emphasized that, in accordance with the standard practice in the industry, various features are not drawn to scale. In fact, the dimensions of the various features may be arbitrarily increased or reduced for clarity of discussion.

FIG. 1 is a simplified block diagram of an embodiment of a VoIP network;

FIG. 2 is a simplified logical block diagram of an embodiment of a system for VoIP call routing; and

FIG. 3 is a simplified flowchart of an embodiment of a method for VoIP call routing.

DETAILED DESCRIPTION

It is to be understood that the following disclosure describes many different examples for implementing different features of various embodiments. Specific examples of components and arrangements are described below to simplify the present disclosure. These are, of course, merely examples and are not intended to be limiting. In addition, the present disclosure may repeat reference numerals and/or letters in the various examples. This repetition is for the purpose of simplicity and clarity and does not in itself dictate a relationship between the various embodiments and/or configurations unless otherwise specified.

FIG. 1 is a simplified block diagram of an embodiment of a VoIP network 10. VoIP network 10 is shown comprising a plurality of media gateway nodes 12-14 interconnected by logical trunk groups 16-18 and the Internet 20, however, it should be understood that the network configuration shown in FIG. 1 is merely exemplary. Logical trunk groups 16-18 comprise a plurality of circuits or transmission channels that are capable of interconnecting telephony calls. Media gateway nodes 12-14 each comprises a plurality of multimedia media gateways (MG) 22-27 coupled to a multimedia gateway controller (MGC) 30-32, which is sometimes referred to as a softswitch. Multimedia gateways 22-27 each may comprise one or more switching fabric of the same or different types for routing telephony calls. The switching fabrics may be packet-switching matrices and/or non-packet switching matrices. The multimedia gateways may be coupled to their respective multimedia gateway controller via an ATM (Asynchronous Transfer Mode) or IP (Internet Protocol) backbone network, for example. Multimedia gateway controllers 30-32 provides call processing control and user interface functions for TDM (Time Division Multiplex), ATM, IP, and other traffic processed, switched and routed by multimedia gateways 22-27. The multimedia gateways coupled to a multimedia gateway controller may be geographically distributed. The VoIP path bearer between the media gateway nodes may comprise ATM, MPLS (Multi-Protocol Label Switching), IP, or other bearer paths. VoIP network 10 enables two users using IP telephone devices such as a telephone operating pursuant to SIP (Session Initiation Protocol) or another suitable protocol to communicate with one another.

The multimedia gateway nodes may convert data from a format, protocol, and/or type required for one network to another format, protocol, and/or type required for another network, and/or otherwise convert data from a first type of data on a first transmission link to a second type of data on a second transmission link. The multimedia gateway nodes may terminate channels from a circuit-switched network and pass streaming media for a packet-switched network, such as Real-Time Transport Protocol (RTP) streams transported via User Datagram Protocol (UDP) in an IP network. Input data for the media gateway may include audio, video, and/or T.120 (real-time multi-point communications), among others, which the media gateway may handle simultaneously or otherwise.

FIG. 2 is a simplified logical block diagram of an embodiment of a system for VoIP call routing 40. System 40 may reside within each multimedia gateway controller. System 40, which may also be referred to as a VoIP call routing engine, comprises at least three logical modules: a VoIP resource manager 42, a data measurement module 44, and a route decision module 46. System 40 is operable to intelligently route VoIP calls around segments of the network that experience congestion, link failure, node failure or other problems. Because voice calls are very sensitive to adverse network conditions that cause packet delay, out-of-order delivery, packet loss and other problems, the avoidance of congested network segments significantly improves the QoS of the VoIP call.

Referring also to FIG. 3, the operation of system 40 is described below. FIG. 3 is a simplified flowchart of an embodiment of a method for VoIP call routing. In step 50, data measurement module 44 actively monitors the call resources to determine their availability and current status. In step 50, a call resource may be defined as a logical trunk group and the local IP endpoint. This call resource may be so defined as a routing object according to object oriented programming. The local IP endpoint may be a local multimedia gateway coupled to the multimedia gateway controller. The state of the routing object is based on the availability of connections between the local IP endpoint to all remote IP endpoints reachable by the respective logical trunk group. For example, the state of the routing object based on multimedia gateway 23 and logical trunk group 16 is based on the aggregated data on connection availability between multimedia gateway 23 to multimedia gateway 24 and to multimedia gateway 25. Therefore, if a determination is made that there is a reliability issue associated with the local IP endpoint communicating with all remote IP endpoints referenced by the respective logical trunk group, then that route object is noted as being congested and not available.

In step 52, data measurement module 44 updates VoIP resource manager 42 on the measured resource status. In step 54, the resource status results is then used to formulate a route list or routing table by VoIP resource manager 42. The route list identifies IP endpoint to IP endpoint routes that are not experiencing problems. The routes in the route list may include IP paths as well as TDM paths. The route list may be prioritized by some predetermined criteria such as reachability and availability. The route list is then made available to route decision module 46 each time it is updated or refreshed. The route list may include TDM paths as well as IP paths. The route list may be prioritized or other organized according to some predetermined criteria, such as availability or amount of congestion. In step 56, for each voice call, route decision module 46 determines the best route based on the route list. The best route may include TDM paths as well as IP paths. In step 58, the voice call is set up and routed using the best route determined by route decision module 46. The best route may be defined as a route that contains paths or segments that best meets a predetermined requirement, such as exceeding a predetermined threshold of availability.

One method to perform resource monitoring and assessment is described in co-pending patent application entitled “System and Method for Determining Network Quality for VoIP Calls,” Attorney Docket No. 34986.36, incorporated herein by reference. However, other means for monitoring and measuring the IP network condition may instead be employed. For example, a connectivity check or diagnostic tool may be used to determine network conditions such as congestion or node/link failure.

As employed herein, the term “network” may be used to refer to an entire network or to a network portion, a network application, and/or network apparatus. To that end, one or more instances of the multimedia gateway and/or softswitch, or components thereof, may be singularly or collectively employed to bridge two or more networks, including those of PSTNs and voice-over-packet (VoP) networks, among others. PSTN networks may employ TDM, among other non-packet formats and/or protocols. VoP networks may employ ATM, VoIP, universal-mobile-telecommunications-service (UTMS), code-division-multiple-access (CDMA, such as CDMA2000 and/or W-CDMA), voice-over-digital-subscriber-line (VoDSL), other formats and/or protocols, and/or combinations thereof.

Previously, there were no routing engines that integrate IP-based networks and traditional voice networks to determine the best route to route voice calls. Voice call routing previously only exists in the voice network domain, which is characterized by logical trunk groups interconnecting switches in the network. Voice routing in this context involves routing on logical trunk groups. The IP network routing function previously only operate in the data network domain and is not operable with the applications operating in the application layer. Information relating to problems detected in the network previously has not been used in routing voice calls. 

1. A method of routing a voice call from a local media gateway to a terminating media gateway, comprising: determining IP network connectivity between the local media gateway and terminating media gateway and generating monitoring results; updating network resource status according to the monitoring results; generating a plurality of routes between the local media gateway and the terminating media gateway in response to the updated network resource status; determining a best route from the plurality of routes; and routing the voice call using the best route.
 2. The method of claim 1, wherein determining IP network connectivity comprises continuously monitoring network connectivity between a local IP endpoint associated with the local media gateway and all IP endpoints reachable by a logical trunk group associated with the local IP endpoint.
 3. The method of claim 1, wherein determining IP network connectivity comprises continuously monitoring network connectivity between all local IP endpoints associated with the local media gateway to all IP endpoints reachable by a logical trunk group associated with the local IP endpoints.
 4. The method of claim 1, wherein generating a plurality of routes comprises generating a plurality of routes comprising data and voice paths.
 5. The method of claim 1, wherein generating a plurality of routes comprises generating a plurality of routes comprising IP and TDM paths.
 6. The method of claim 1, wherein determining a best route comprises selecting a route that best meets a predetermined criteria.
 7. The method of claim 1, wherein determining a best route comprises selecting a route that is least congested.
 8. A method of routing a VoIP call from a local IP endpoint to a terminating switch, comprising: defining a routing object having the local IP endpoint and a logical trunk group associated with the local IP endpoint; determining the state of the routing object; and routing the VoIP call based on the state of the routing object.
 9. The method of claim 8, wherein determining the state of the routing object comprises determining connection between the local IP endpoint and all remote IP endpoints reachable by the logical trunk group.
 10. The method of claim 8, further comprising generating a plurality of routes between the local IP endpoint and the terminating switch in response to at least the state of the routing object.
 11. The method of claim 10, further comprising determine a best route from the plurality of routes.
 12. The method of claim 10, wherein generating a plurality of routes comprises generating a plurality of IP, TDM and IP/TDM routes.
 13. The method of claim 10, wherein determining a best route comprises selecting a route that best meets a predetermined criteria.
 14. The method of claim 10, wherein determining a best route comprises selecting a route that is least congested.
 15. A VoIP call routing engine comprises: a data measurement module operable to monitor network connectivity between a local IP endpoint and a terminating media gateway and generating monitoring results; a VoIP resource manager operable to generate a plurality of routes between the local IP endpoint and the terminating media gateway in response to the monitoring results; and a route decision module operable to determine a best route from the plurality of routes and route the VoIP call using the best route.
 16. A method of routing a VoIP call comprising: means for continuously monitoring network connectivity between a local IP endpoint and a terminating switch and generating monitoring results; means for updating network resource status according to the monitoring results; means for generating a plurality of routes between the local IP endpoint and the terminating switch in response to the updated network resource status; means for determine a best route from the plurality of routes; and means for routing the VoIP call using the best route.
 17. The VoIP call routing engine of claim 15, further comprising a routing object associated with the local IP endpoint and a logical trunk group.
 18. A VoIP system comprising: a logical trunk group between a local IP endpoint and a media gateway; a data measurement module operable to monitor network connectivity between the local IP endpoint and the media gateway and generating monitoring results; a VoIP resource manager operable to generate a plurality of routes between the local IP endpoint and the media gateway via mapping a logical circuit contained in the logical trunk group to the IP endpoint, in response to the monitoring results; and a route decision module operable to determine a best route from the plurality of routes and route the VoIP call using the best route. 